Maisie Williams will make a third appearance in 'Doctor Who'.

Maisie Williams

Maisie Williams

It has been confirmed by the BBC One programme's showrunner Steven Moffat that the 'Game of Thrones' star will return as immortal viking Ashildir for dramatic episode 'Face The Raven,' when the Doctor's companion Clara Oswald (Jenna Coleman) is expected to face her death.

During the episode 'The Woman Who Lived' where she portrayed The Highwayman, she told the Doctor - played by Peter Capaldi: "Someone has to look out for the people you abandon, who better than me? I'll be the patron saint of the Doctor's leftovers. While you're busy protecting this world, I'll get busy protecting it from you."

To which he replied: "Ashildir, I think I'm very glad I saved you."

Meanwhile, Jenna previously insisted the 18-year-old actress "fit right in" when she joined the cast for the new series.

When asked if things are different between herself and Peter when they have guest stars on set, she said: "The two of us are always behaving as stupidly as we do, it's been lovely having Michelle [Gomez] back, she's always a laugh. Maisie is wonderful, I was a really big fan of hers before she came to 'Doctor Who', she fits right in so it's been really great having her join us. One of the most wonderful things about the show is every episode feels so different, it feels like a whole new show in a way."